U.S. patent number 6,682,532 [Application Number 10/105,109] was granted by the patent office on 2004-01-27 for coupling system and method for extending spinal instrumentation.
This patent grant is currently assigned to DePuy Acromed, Inc.. Invention is credited to Robert G. Johnson, Richard C. Techiera.
United States Patent |
6,682,532 |
Johnson , et al. |
January 27, 2004 |
Coupling system and method for extending spinal instrumentation
Abstract
A coupler for connecting a first, slotted, implanted spinal
fixation element to a second spinal fixation element includes a
post and a head disposed on a distal end of the post. The head of
the coupler has a width shorter than a width of a slot in the
first, slotted, implanted spinal fixation element, and a length
longer than the width of the slot in the first, slotted, implanted
spinal fixation element. The coupler with a head so configured can
be placed in a first orientation so that the head passes through
the slot in the first, slotted, implanted spinal fixation element,
and then can be placed in a second orientation wherein the head is
trapped beneath the first, slotted, implanted spinal fixation
element while the post having a connecting element extends through
the slot. Systems and methods for extending a first, implanted
spinal fixation element to one or more additional vertebrae while
leaving the first, implanted spinal fixation element in place are
also disclosed.
Inventors: |
Johnson; Robert G. (San
Antonio, TX), Techiera; Richard C. (New Bedford, MA) |
Assignee: |
DePuy Acromed, Inc. (Raynham,
MA)
|
Family
ID: |
28040787 |
Appl.
No.: |
10/105,109 |
Filed: |
March 22, 2002 |
Current U.S.
Class: |
606/264; 606/278;
606/279; 606/286 |
Current CPC
Class: |
A61B
17/7007 (20130101); A61B 17/701 (20130101); A61B
17/7041 (20130101) |
Current International
Class: |
A61B
17/70 (20060101); A61B 017/56 (); A61B 017/58 ();
A61F 002/30 () |
Field of
Search: |
;606/61,69,70,71,72,73 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
T Glenn Pait, MD., et al. "Inside-outside technique for posterior
occipitocervical spine instrumentation and stabilization:
preliminary results", J. Neurosurg: Spine/vol. 90(1-7) Jan.,
1999..
|
Primary Examiner: Robert; Eduardo C.
Assistant Examiner: Ramana; Anuradha
Attorney, Agent or Firm: Nutter, McClennen & Fish,
LLP
Claims
What is claimed is:
1. A coupler for connecting a first, slotted, implanted spinal
fixation element to a second spinal fixation element, the coupler
comprising: a post and a head disposed on a distal end of the post,
the head having a width shorter than a width of a slot in the
first, slotted, implanted spinal fixation element and a length
longer than the width of the slot in the first, slotted, implanted
spinal fixation element, the post having a connecting element;
wherein when placed in a first orientation, the head passes through
the slot in the first, slotted, implanted spinal fixation element,
and when then placed in a second orientation, the head is trapped
beneath the first, slotted, implanted spinal fixation element while
the connecting element extends through the slot.
2. The coupler according to claim 1 wherein a proximal end of the
post includes a driver element for connecting to a driver to rotate
the coupler from the first orientation to the second
orientation.
3. The coupler according to claim 1 wherein a proximal end of the
post includes a visual indicator element indicating the rotational
orientation of the coupler.
4. The coupler according to claim 1 wherein at opposed lengthwise
ends, the head is radiused and beveled to facilitate rotation of
the coupler.
5. The coupler according to claim 1 wherein a proximal face of the
head includes surface features disposed thereon to increase
friction between the coupler and the first, slotted, implanted
spinal fixation element when the coupler is tightened thereto.
6. The coupler according to claim 1 wherein the connecting element
comprises threads disposed on the post along a length thereof and a
nut disposed on the threads for fixing the coupler to the first,
slotted, implanted spinal fixation element after placement of the
head in the second orientation.
7. The coupler according to claim 6 wherein the connecting element
further comprises a beveled element having a bevel corresponding to
a scallop provided on a proximal facing surface of the first,
slotted, implanted spinal fixation element adjacent to the slot
wherein upon tightening of the nut, the beveled element cooperates
with the scallop to prevent relative movement of the coupler along
a length of the slot.
8. A system for extending a first, implanted spinal fixation
element to one or more additional adjacent vertebrae while leaving
the first, implanted spinal fixation element in place, the system
comprising: a second spinal fixation element; a coupler having a
connecting member and a head disposed on a distal end of the
connecting member for holding the coupler to a slot on the first,
implanted spinal fixation element, the head having a width shorter
than a width of the slot in the first, implanted spinal fixation
element and a length longer than the width of the slot in the
first, implanted spinal fixation element; and a second spinal
fixation element attachment member having a coupler attaching
portion for attaching to the connecting member of the coupler and a
second spinal fixation element attaching portion; wherein assembly
of the coupler to the first, implanted spinal fixation element, the
second spinal fixation element attachment member to the coupler,
and the second spinal fixation element attachment member to the
second spinal fixation element extends the first, implanted spinal
fixation element to one or more adjacent vertebrae while leaving
the first, implanted spinal fixation element in place.
9. The system according to claim 8 wherein a proximal end of the
connecting member includes a driver element for connecting to a
driver to rotate the coupler from the first orientation to the
second orientation.
10. The system according to claim 8 wherein a proximal end of the
connecting member includes a visual indicator element indicating
the rotational orientation of the coupler.
11. The system according to claim 8 wherein at opposed lengthwise
ends, the head is radiused and beveled to facilitate rotation of
the coupler.
12. The system according to claim 8 wherein a proximal face of the
head includes surface features disposed thereon to increase
friction between the coupler and the first, implanted spinal
fixation element when the coupler is tightened thereto.
13. The system according to claim 8 wherein the connecting member
comprises a threaded post and a nut disposed on the threads for
fixing the coupler to the first, implanted spinal fixation element
after placement of the head in the second orientation.
14. The system according to claim 13 wherein the connecting member
further comprises a beveled element having a bevel corresponding to
a scallop provided on a proximal facing surface of the first,
implanted spinal fixation element adjacent to the slot wherein upon
tightening of the nut, the beveled element cooperates with the
scallop to prevent relative movement of the coupler along a length
of the slot.
15. The system according to claim 8 wherein the second spinal
fixation element is a spinal fixation rod.
16. The system according to claim 15 wherein the second spinal
fixation element attaching portion of the second spinal fixation
element attachment member defines a bore for accepting and
attaching the spinal fixation rod.
17. The system according to claim 16, wherein the connecting member
comprises a threaded post and the coupler attaching portion of the
second spinal fixation element attachment member defines a bore for
accepting the threaded post and a nut for holding the second spinal
fixation element attachment member to the connecting member.
18. A system for extending a first, implanted spinal fixation
element to one or more additional adjacent vertebrae while leaving
the first, implanted spinal fixation element in place, the system
comprising: a first, implanted spinal fixation element attached to
a patient's spine and having a slot thereon; a second spinal
fixation element; a coupler having a connecting member and a head
disposed on a distal end of the connecting member for holding the
coupler to the slot on the first, implanted spinal fixation
element, the head having a width shorter than a width of the slot
in the first, implanted spinal fixation element and a length longer
than the width of the slot in the first, implanted spinal fixation
element, wherein when placed in a first orientation, the head
passes through the slot, and when then placed in a second
orientation, the head is trapped beneath the first, implanted
spinal fixation element while the connecting member extends through
the slot; and a second spinal fixation element attachment member
having a coupler attaching portion for attaching to the connecting
member of the coupler and a second spinal fixation element
attaching portion; wherein assembly of the coupler to the slot on
first, implanted spinal fixation element, the second spinal
fixation element attachment member to the coupler, and the second
spinal fixation element attachment member to the second spinal
fixation element extends the first, implanted spinal fixation
element to one or more adjacent vertebrae while leaving the first,
implanted spinal fixation element in place.
19. The system according to claim 18 wherein the second spinal
fixation element is a spinal fixation rod and the second spinal
fixation element attaching portion of the second spinal fixation
element attachment member defines a bore for accepting and
attaching the spinal fixation rod.
20. A method for extending a first, implanted spinal fixation
element to one or more additional adjacent vertebrae while leaving
the first, implanted spinal fixation element in place, the method
comprising: providing a first, implanted spinal fixation element
having a slot; assembling a coupler having a connecting member and
a head disposed on a distal end of the connecting member for
holding the coupler to the slot on the first, implanted spinal
fixation element, the head having a width shorter than a width of
the slot in the first, implanted spinal fixation element and a
length longer than the width of the slot in the first, implanted
spinal fixation element; assembling a second spinal fixation
element attachment member having a coupler attaching portion for
attaching to the connecting member of the coupler and a second
spinal fixation element attaching portion to the coupler;
assembling a second spinal fixation element to the second spinal
fixation element attachment member; and fixing the second spinal
fixation element to the one or more additional adjacent vertebrae;
wherein the first, implanted spinal fixation element is left in
place.
21. The method according to claim 20 wherein the step of assembling
the coupler to the first, implanted spinal fixation element
includes placing the coupler in a first orientation wherein the
head passes through the slot, passing the head through the slot,
and placing the coupler in a second orientation wherein the head is
trapped beneath the first, implanted spinal fixation element while
the connecting member extends through the slot.
22. The method according to claim 20 wherein the second spinal
fixation element is a spinal fixation rod and the second spinal
fixation element attaching portion of the second spinal fixation
element attachment member defines a bore for accepting and
attaching the spinal fixation rod; the step of assembling the
second spinal fixation element to the to the second spinal fixation
element attachment member including fixing the rod within the bore.
Description
FIELD OF THE INVENTION
The present invention relates to devices, systems and methods that
aid in the performance of spinal revision surgery in which
previously implanted spinal fixation instrumentation is extended to
additional vertebrae. More particularly, the invention provides
coupling systems and methods that allow for a first, implanted
spinal fixation element to be coupled to a second spinal fixation
element while leaving the first element in place.
BACKGROUND OF THE INVENTION
The use of spinal fixation instrumentation to align and/or fix a
desired relationship between adjacent vertebral bodies is well
established. Such instrumentation typically includes a spinal
fixation element, such as a relatively rigid plate or a rod, that
is coupled to adjacent vertebrae by attaching the element to
pedicle screws which have been inserted into the patient's
vertebrae. Once installed, the spinal fixation instrumentation
holds the vertebrae in a desired spatial relationship, either until
desired healing or spinal fusion has taken place, or for some
longer period of time.
While use of such spinal fixation instrumentation is effective in
treating a number of spinal disorders and traumas, it sometimes
becomes necessary to extend the instrumentation from the vertebrae
being treated to one or more additional adjacent vertebrae. This
can be accomplished by removing the existing spinal fixation
element (in particular, removing the rod(s) or plate(s) that fix
the alignment of the previously treated vertebrae), and replacing
it with a new element configured to treat all of the vertebrae
needing treatment. Spinal fixation elements, however, are carefully
shaped and placed to result in a desired alignment. Accordingly,
removal, or even sometimes movement, of a spinal fixation element
can result in significant effort by a surgeon to realign the
previously aligned vertebrae and instrumentation, in addition to
treating additional vertebrae. In addition, it is preferable not to
remove implanted pedicle screws as the replacement of such screws
in the patient's vertebrae can result in the removal of additional
bone material from the patient's spine.
Accordingly, there is a need for a coupling system and method for
extending previously implanted spinal instrumentation to additional
vertebrae without removing the existing instrumentation. In
particular, coupling systems and methods that can couple a second
spinal fixation element to a first, implanted spinal fixation
element while leaving the first element in place would simplify
revision surgery for the surgeon, and likely provide many benefits
for the patient as well.
SUMMARY OF THE INVENTION
The present invention solves the described problems in the art and
others by providing a coupler for connecting a first, slotted,
implanted spinal fixation element to a second spinal fixation
element. In a first aspect, the invention includes a coupler having
a post and a head disposed on a distal end of the post. The head of
the coupler has a width shorter than a width of a slot in the
first, slotted, implanted spinal fixation element, and a length
longer than the width of the slot in the first, slotted, implanted
spinal fixation element. The coupler with a head so configured can
be placed in a first orientation so that the head passes through
the slot in the first, slotted, implanted spinal fixation element,
and then can be placed in a second orientation wherein the head is
trapped beneath the first, slotted, implanted spinal fixation
element while the post having a connecting element extends through
the slot. In this way, a coupler can be provided for connecting a
second spinal fixation element without removing the first, slotted,
implanted spinal fixation element.
In a further aspect of the invention, a system for extending a
first, implanted spinal fixation element to one or more additional
adjacent vertebrae while leaving the first, implanted spinal
fixation element in place is provided. The system includes a second
spinal fixation element, a coupler, and a second spinal fixation
element attachment member. The coupler has a connecting member and
a head disposed on a distal end of the connecting member for
holding the coupler to the first, implanted spinal fixation
element. The second spinal fixation element attachment member has a
coupler attaching portion for attaching to the connecting member of
the coupler and a second spinal fixation element attaching portion.
In this system, when the coupler is assembled to the first,
implanted spinal fixation element, the second spinal fixation
element attachment member is assembled to the coupler, and the
second spinal fixation element is assembled to the second spinal
fixation element; the system extends spinal treatment from the
first, implanted spinal fixation element to one or more adjacent
vertebrae while leaving the first, implanted spinal fixation
element in place.
In one embodiment of this aspect of the invention, the first,
implanted spinal fixation element is slotted and the head of the
coupler is configured to hold the coupler to a slot on the first,
implanted spinal fixation element. In this embodiment, the head has
a width shorter than a width of the slot in the first, implanted
spinal fixation element, and a length longer than the width of the
slot in the first, implanted spinal fixation element. When this
coupler is placed in a first orientation, the head passes through
the slot, and when the coupler is then placed in a second
orientation, the head is trapped beneath the first, implanted
spinal fixation element while the connecting member extends through
the slot.
In a further embodiment of this aspect of the invention, the second
spinal fixation element can be a spinal fixation rod and the second
spinal fixation element attaching portion of the second spinal
fixation element attachment member can define a bore for accepting
and attaching the spinal fixation rod.
In a further aspect of the invention, a method is provided for
extending a first, implanted spinal fixation element to one or more
additional adjacent vertebrae while leaving the first, implanted
spinal fixation element in place. The method includes assembling a
coupler having a connecting member and a head disposed on a distal
end of the connecting member for holding the coupler to the first,
implanted spinal fixation element; assembling a second spinal
fixation element attachment member having a coupler attaching
portion for attaching to the connecting member of the coupler and a
second spinal fixation element attaching portion to the coupler;
assembling a second spinal fixation element to the second spinal
fixation element attachment member; and fixing the second spinal
fixation element to the one or more additional adjacent vertebrae.
Each of the steps in this method can be performed while the first,
implanted spinal fixation element is left in place.
In one embodiment of this aspect of the invention, the first,
implanted spinal fixation element is slotted and the head of the
coupler is configured to hold the coupler to a slot on the first,
implanted spinal fixation element. The head has a width shorter
than a width of the slot in the first, implanted spinal fixation
element, and a length longer than the width of the slot in the
first, implanted spinal fixation element. The step of assembling
the coupler to the first, implanted spinal fixation element can
thus include placing the coupler in a first orientation wherein the
head passes through the slot, passing the head through the slot,
and placing the coupler in a second orientation wherein the head is
trapped beneath the first, implanted spinal fixation element while
the connecting member extends through the slot.
In a further embodiment of this aspect of the invention, the second
spinal fixation element is a spinal fixation rod and the second
spinal fixation element attaching portion of the second spinal
fixation element attachment member defines a bore for accepting and
attaching the spinal fixation rod. In this embodiment, the step of
assembling the second spinal fixation element to the to the second
spinal fixation element attachment member includes fixing the rod
within the bore.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be more fully understood from the following
detailed description taken in conjunction with the accompanying
drawings:
FIG. 1 illustrates exemplary implanted spinal fixation
instrumentation known in the art with which the invention may be
used;
FIG. 2 illustrates a spinal fixation element used in the
instrumentation of FIG. 1;
FIG. 3 illustrates a bone coupling element used in the
instrumentation of FIG. 1;
FIG. 4 illustrates a T-coupler of the invention;
FIG. 5 illustrates the T-coupler of FIG. 4 interacting with the
spinal fixation element of FIG. 2 in a first orientation;
FIG. 6 illustrates the T-coupler of FIG. 4 interacting with the
spinal fixation element of FIG. 2 in a second orientation;
FIG. 7 illustrates the T-coupler of FIG. 4 with fixation
hardware;
FIG. 8 illustrates a system of the invention for fixing a first
implanted spinal fixation element to a second spinal fixation
element; and
FIG. 9 illustrates a second spinal fixation coupling element and
second spinal fixation element of FIG. 8.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides systems and methods useful for
coupling a first, implanted spinal fixation element to a second
spinal fixation element so that existing spinal fixation treatment
may be extended to additional adjacent vertebrae without removing
the implanted spinal fixation element. A pair of common spinal
fixation elements 30, slotted plates in this embodiment, are
illustrated as implanted to a patient's spine 24 in FIG. 1.
Illustrated spinal fixation elements 30 (one spinal fixation
element 30 is further illustrated in FIG. 2) are coupled to several
vertebrae 22 (specifically, to vertebrae 22c, 22a, and 22b in
descending order in FIG. 1) by spinal coupling assemblies 32
(illustrated in further detail in FIG. 3).
Exemplary spinal plates 30 (FIGS. 1 and 2; and further described in
U.S. Pat. No. 4,611,581 to Steffee which is hereby incorporated by
reference) include slots 52 through which spinal coupling
assemblies 32 may extend. Spinal plates 30 generally include a pair
of parallel longitudinally (in the direction of the spine when the
plates are implanted) extending beam sections 88, 90 which are
interconnected by a plurality of cross sections 94, 96, 98, 100,
102, and 104. The cross sections 94-104 cooperate with beam
sections 88, 90 to define slots 52 having a width 118. Slots 52 can
include beveled edge portion 114 and can also include a plurality
of scallops or recesses 116.
Exemplary spinal coupling assembly 32 (FIGS. 1 and 3; also further
described in U.S. Pat. No. 4,611,581 to Steffee which is
incorporated by reference above) includes a bone coupling element
40 and a nut 42. Bone coupling element 40 includes a distal bone
engaging thread 44 which is configured to hold the coupling element
to a vertebral body. Bone coupling element 40 also includes a
proximal threaded region 46 configured to be threadedly engaged to
nut 42. Bone coupling element 40 can also include a proximal
driving element 48.
In use, a series of holes are formed in adjacent vertebrae, each
hole being narrower in width than the distal threads 44 on bone
coupling element 40, and a bone coupling element is screwed into
each of the holes to fix the bone coupling elements to the
vertebrae while leaving proximal thread 46 extending outside the
bone. Spinal fixation element 30 is shaped as desired and placed so
that extending proximal threads 46 of the implanted bone coupling
elements 40 pass through slots 52, and nuts 42 are screwed onto
proximal threads 46 to hold spinal fixation element 30 to the
vertebrae. In one embodiment, a side of nut 42 facing spinal
fixation element 30 is tapered so as to cooperate with scallops 116
on the spinal fixation element so that, upon tightening, nuts 42
can also fix the spinal fixation element or elements in a
longitudinal direction.
A coupling element 120 of the invention, sometimes referred to
herein as a "T-coupler" because of the shape of the illustrative
embodiment, for coupling an implanted spinal fixation element such
as spinal fixation element 30 (illustrated as implanted in FIG. 1)
to a second spinal fixation element is illustrated in FIG. 4.
T-coupler 120 has a head 122 and post 124. Head 122 is shaped so as
to fit through a slot in an implanted spinal fixation element, such
as slot 52 in spinal fixation element 30, so that head 122 can pass
through slot 52 in a first orientation (illustrated in FIG. 5), but
does not pass through when head 122 is placed in a second
orientation (illustrated in FIG. 6). In the illustrated embodiment,
head 122 has a width 126 that is smaller than width 118 of slot 52,
allowing the head to pass through when the head is aligned so that
head width 126 fits through slot width 118. Head 122 also has a
length 128 that is larger than slot width 118 so that when the head
is oriented so that its length is aligned with slot width 118, the
head does not pass through the slot.
In use, head 122 is appropriately oriented and passed through the
slot of an implanted fixation element (FIG. 5), then rotated
approximately 90.degree. so that head 122 is trapped beneath the
spinal fixation element (between the spinal fixation element and
the spine) while post 124 of T-coupler 120 extends outward from the
spinal fixation element. A driving element 130, in this embodiment
a hex-head, can be provided on post 124 for orienting T-coupler 120
after passing head 122 though slot 52, and a visual indicator 132
(a groove in the illustrated embodiment) can also be provided so
that a surgeon or other operator can readily determine the
orientation of head 122.
Illustrated head 122 of T-coupler 120 includes several additional
features to facilitate its use as described above. Both ends 134 of
head 122 can have a full radius at their edges to facilitate
rotational orientation of the head, and one or more bevels 136 can
also be provided proximate to each end 134. V-grooves 138 or other
surface features can be provided on the "top" surface of head 122
(the surface that will abut the back of the implanted spinal
fixation member) to encourage head 122 to remain in a fixed
position with respect to the implanted spinal fixation member upon
tightening of T-coupler to the fixation element.
T-coupler 120 is illustrated in FIG. 7 with hardware appropriate
for using the T-coupler to fix a first spinal fixation element to a
second spinal fixation element coupler. T-coupler 120 is provided
in this embodiment with a conical washer 140, a T-coupler fixing
nut 142, and a second spinal fixation element coupler fixing nut
144. After placement and orientation of T-coupler 120 with respect
to spinal fixation element 30, washer 140, which can be tapered to
cooperate with scallops 116, is placed over post 124, followed by
T-coupler fixing nut 142 which can be threadedly engaged with post
124 and tightened to fix T-coupler 120 to fixation element 30. In
one embodiment, post 124 can be sized and threaded similarly to
proximal threaded region 46 of bone coupling element 40 so that the
same hardware and instrumentation (such as, for example, the
washers, nuts, and hex drivers) used with the existing or
to-be-installed spinal fixation instrumentation can also be used
with T-coupler 120.
In the embodiment illustrated in FIGS. 4 and 7, T-coupler 120 head
122 can have a length 128 of approximately 12 millimeters, a width
126 less than approximately 5 millimeters (such as between
approximately 4.83 and 4.98 millimeters), and a height of
approximately 2 millimeters, while post 124 can have a major
diameter approximately equal to the head width 126, and a threaded
length of approximately 17 millimeters with a driving element 130
height of approximately 3.18 millimeters for a total overall
T-coupler height of approximately 22.18 millimeters. A person of
ordinary skill in the art will recognize that these illustrative
dimensions can be varied within the spirit of the invention,
however, the height of T-coupler 120 head 122 must be kept
sufficiently small to fit between the implanted spinal fixation
device and a patient's vertebral body in order to be effective as
described. All of the illustrated hardware can be formed from
materials known in the art to be inert when implanted in the body
and having sufficient strength to perform the desired fixation such
as stainless steel, titanium, and alloys thereof.
T-coupler 120 is used to fix a first spinal fixation element 30 to
a second spinal fixation element 148 in FIG. 8. T-coupler 120 is
fixed to spinal fixation element 30 as described above leaving post
124 of the T-coupler extending upward after placement and
tightening of washer 140 and nut 142. A second spinal fixation
coupling element 146 is then placed over post 124 and fixed with
nut 144. A second spinal fixation element 148 is coupled to the
second spinal fixation coupling element, typically though not
necessarily before tightening nut 144.
An exemplary second spinal fixation coupling element 146 and second
spinal fixation element 148 are further illustrated in FIG. 9. In
this embodiment, second spinal fixation element 148 is a spinal
fixation rod and second spinal fixation coupling element 146 is a
slotted rod connector defining a rod receiving bore 156. Slotted
rod connector 146 includes first and second tines 150, 152 through
which a hole 154 is formed. Slotted rod connector 146 can be placed
over post 124 using hole 154, then tightening of nut 144 will
tighten slotted rod connector 146 both to T-coupler 120 and to
second spinal fixation element 148, thus effecting a secure
connection between a first, implanted spinal fixation element 30
and a second spinal fixation element 148. Further examples of rod
connectors useful with the invention can be found in U.S. Pat. No.
4,648,388 to Steffee; U.S. Pat. No. 6,080,156 to Asher et al.; U.S.
Pat. No. 5,474,551 to Finn et al.; and U.S. Pat. No. 5,810,816 to
Roussouly et al.; each of which is incorporated herein by
reference.
In one embodiment, the systems and methods described herein can be
used to couple a first implanted spinal fixation element, for
example, a VSP.RTM. Plate system available from DePuy AcroMed Inc.
of Raynham Mass., to a known second spinal fixation element, such
as an ISOL.RTM. Rod system also available from DePuy AcroMed Inc.,
while minimizing the amount of additional hardware to be stocked by
the hospital or other healthcare organization where such systems
are used. The second spinal fixation element can then be used to
fix additional vertebrae according to the configuration and
intended use of the second spinal fixation element using means
understood by persons of ordinary skill in the art.
Using the system further described above, a method of the invention
for extending a first, implanted spinal fixation element to one or
more additional adjacent vertebrae while leaving the first,
implanted spinal fixation element in place can include the steps of
assembling a coupler having a connecting member and a head disposed
on a distal end of the connecting member for holding the coupler to
the first, implanted spinal fixation element; assembling a second
spinal fixation element attachment member having a coupler
attaching portion for attaching to the connecting member of the
coupler and a second spinal fixation element attaching portion to
the coupler; assembling a second spinal fixation element to the
second spinal fixation element attachment member; and fixing the
second spinal fixation element to the one or more additional
adjacent vertebrae. Each of the steps in this method can be
performed while the first, implanted spinal fixation element is
left in place, and a person of ordinary skill in the art will
recognize that the order of these steps may be varied in keeping
with the spirit of the invention.
Where the first, implanted spinal fixation element is slotted and
the head of the coupler is configured to hold the coupler to a slot
on the first, implanted spinal fixation element, the head has a
width shorter than a width of the slot in the first, implanted
spinal fixation element, and a length longer than the width of the
slot in the first, implanted spinal fixation element. The step of
assembling the coupler to the first, implanted spinal fixation
element can thus include placing the coupler in a first orientation
wherein the head passes through the slot, passing the head through
the slot, and placing the coupler in a second orientation wherein
the head is trapped beneath the first, implanted spinal fixation
element while the connecting member extends through the slot.
In addition, where the second spinal fixation element is a spinal
fixation rod and the second spinal fixation element attaching
portion of the second spinal fixation element attachment member
defines a bore for accepting and attaching the spinal fixation rod,
the step of assembling the second spinal fixation element to the to
the second spinal fixation element attachment member includes
fixing the rod within the bore.
A person of ordinary skill in the art will appreciate further
features and advantages of the invention based on the
above-described embodiments. Accordingly, the invention is not to
be limited by what has been particularly shown and described,
except as indicated by the appended claims. All publication and
references cited herein are expressly incorporated herein by
reference in their entity.
* * * * *